Subject: Re: [PATCH] ARM: Thumb2: align ALT_UP() sections sufficiently

From: "Russell King (Oracle)" <[email-masked]>
Date: Tue, 18 Jan 2022 11:21:20 +0000

On Tue, Jan 18, 2022 at 11:27:56AM +0100, Ard Biesheuvel wrote:
> When building for Thumb2, the .alt.smp.init sections that are emitted by
> the ALT_UP() patching code may not be 32-bit aligned, even though the
> fixup_smp_on_up() routine expects that. This results in alignment faults
> at module load time, which need to be fixed up by the fault handler.
> 
> So let's align those sections explicitly, and avoid this from occurring.

Are you seeing a problem that this patch fixes?

This really should not matter. .alt.smp.init contents are always a whole
number of 32-bit words. These are gathered by the linker into the
.init.smpalt section, so the contents should always be a whole number
of 32-bit words.

This follows the .init.tagtable section, which is also a 32-bit word
aligned structure built by the linker... which follows the
.init.arch.info section and .init.proc.info sections which all have
32-bit alignment requirements.

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